1. Field of the Invention
The present invention relates to a semiconductor device in which an interlayer insulating film having a low dielectric constant is formed to cover a copper wiring, and a method of manufacturing the same.
2. Description of the Prior Art
In recent years, with the progress of the higher integration and the higher density of the semiconductor integrated circuit device, the higher speed of the data transfer rate is requested. For this reason, the insulating film having the low dielectric constant to give the small RC delay (referred to as a xe2x80x9clow dielectric constant insulating filmxe2x80x9d hereinafter) is employed. For example, there are the SiOF film having the relative dielectric constant of 3.5 to 3.8, the porous SiO2 film having the relative dielectric constant of 3.0 to 3.1, etc.
In contrast, the wiring material is being changed from the conventional aluminum (Al) to the copper (Cu) wiring having the low electric resistance.
Accordingly, in order to manufacture the semiconductor device having the conventional multi-layered copper wiring, the low dielectric constant insulating film is formed as the interlayer insulating film on the copper wiring. However, since normally the copper is easily diffused into the low dielectric constant insulating film from the copper wiring, the leakage current between the upper and lower wirings is increased. Therefore, in order to prevent the diffusion of the copper element into the low dielectric constant insulating film, the development of the SiC-based barrier insulating film is carried out at the same time.
The semiconductor device having the copper wirings has a constitution that the SiC-based barrier insulating film and the low dielectric constant insulating film are laminated in sequence on the copper wirings.
However, although its relative dielectric constant is relatively low such as about 5, the SiC-based barrier insulating film cannot sufficiently suppress the increase in the leakage current. In this case, in order to enoughly suppress the leakage current, the oxygen must be introduced much more into the SiC-based barrier insulating film.
If to do so, the leakage current can be reduced up to the satisfactory level, nevertheless such a new problem is caused that the surface of the copper wiring is oxidized and thus the barrier insulating film and the low dielectric constant insulating film is ready to peel.
It is an object of the present invention to provide a semiconductor device capable of reducing a leakage current between copper wirings which sandwich an interlayer insulating film between them while preventing peeling-off of the interlayer insulating film when the interlayer insulating film made of a multi-layered insulating film having a low dielectric constant is formed between the copper wirings, and a method of manufacturing the same.
The insulating film that comes into contact with the wiring of the multi-layered wiring constituting the interlayer insulating film is formed by plasmanizing the film forming gas containing the alkyl compound having the siloxane bond and any one oxygen-containing gas of N2O, H2O, and CO2, whose flow rate is equal to or less than the flow rate of the alkyl compound gas, to react mutually.
Since the insulating film is formed by the plasma enhanced CVD method using the film forming gas containing the alkyl compound having the siloxane bond or the plasma enhanced CVD method using the alkyl compound having the siloxane bond and the gas containing the hydrocarbon, the dense insulating film having the low dielectric constant can be formed.
Particularly, the film having the high density can be formed by employing the parallel-plate type plasma film forming apparatus, then connecting at least the low frequency power supply to the electrode side that holds the substrate, and then applying the low frequency power to the substrate.
Also, since the gas containing a small amount of oxygen is employed as the oxygen-containing gas serving as the oxidizing agent and also the flow rate of the oxygen-containing gas is set equal to or smaller than the flow rate of the alkyl compound, the oxidation of the copper wiring, a relative amount of oxygen in the film forming gas can be reduced. Therefore, the oxidation of the copper wiring, for example, can be prevented in forming the film. In addition, when the copper wiring is covered with a barrier insulating film and then other interlayer insulating film having the low dielectric constant is formed on the barrier insulating film, the barrier insulating film can prevents the copper wiring from being oxidized even if the oxygen-containing gas is contained in the film forming gas.
Further, the barrier insulating film formed as described above is dense. Thus, if such barrier insulating film is inserted between the upper and lower copper wirings, the leakage current between the copper wirings between which the interlayer insulating film is sandwiched can be reduced by preventing the diffusion of the copper into the interlayer insulating film from the copper wiring, and also the dielectric constant of the overall interlayer insulating film can be reduced.
As described above, according to the present invention, it is possible to form the interlayer insulating film that is dense, and results in the small leakage current between the copper wirings which sandwich the interlayer insulating film, and has the low dielectric constant.